Tuning unit



Dec. 27, 1949 1 5.. H. VAN BILLIARD TUNING UNIT 2 Sheets-Sheet 1 Filed Sept. 20, 1946 Invetov': Lewis I-I. VanBllaYd,

' His Attorney.

Dec. 27, 1949 .1.. H. VAN BILLIARD TUNING UNIT 2 Sheets-Sheet 2 Filed Sept. 20, 1946 Patented lDer.. 27, 1949 TUNING UNIT Lewis H. Van Billiard, Newtown, Conn., assignor to General Electric Company, a corporation of New York Application`September 20, 1946, Serial No. 698,357

6 Claims. l

My invention relates to tuning systems for radio apparatus and, more particularly, to tuning unit for radio apparatus adapted to receive both long and short wavelengths.

In radio receivers adapted to receive w-aves over bands separated greatly in frequency, such as the broadcast band and the high frequency frequency modul-ation ban-d, tuning of the circuits of such receivers over all of the desired bands presents serious problems. If it is attempted to Aprovide such tuning by the use of unicontrolled variable condensers as heretofore employed, itis necessary that the elements for tuning different portions of the receiver circuits be insulated from each other so that there is no coupling either inductively or through a common tuning shaft. Another serious problem is the size of the tuning unit -which must be relatively compact and in which, furthermore, all of the parts must be accessible so that connection to the remaining -portions of the receiver circuit may be m-ade by very short leads or connections. In addition, it is most desirable that any tuning unit be free from mechanical resonance conditions. Accordingly, it is a primary object of my invention to provide a new and improved tuning unit for a radio receiver adapted to receive oscillations Varying over an extremely wide range of frequencies.

It is still another object of my invention to provide a new an improved tuning un'it for a radio receiver in which tuning is effected solely by means of a linear or translating motion.

It is a still further object of my invention to provide a new and improved tuning system for a radio receiver in which all movable portions of the tuning element have no conductive connection with the other elements of the receiver circuit.

It is a still further object of my invention to provide a new and improved tuning unit for a radio receiver comprising component parts which may be easily manufactured and assembled and which require little skill either in the assembly or in their connection with a radio receiver.

It is still another object of my invention to provide ya new yand improved tuning -unit for a radio receiver operated over a plurality of bands in which the movable parts of all the tuning elements are freely suspended and tuning is effected by allowing the movable parts to descend in a straight line with respect to the fixed parts of the tuning elements.

One of the features of my invention consists in so suspending a plurality of elements adapted to tune the respective circuits of a radio receiver that the circuits may be varied over a wide range of frequency merely by allowing the tuning elements to descend substantially freely. A plurality of coils and iron cores are employed for tuning the receiver circuits to 1ower frequencies and a plurality of inductively coupled metallic bars are adapted to be tuned by fiat plates or vanes which descend between the bars to tune the receiver lcircuits over a range of high frequencies such as those employed in the frequency modulation band.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims. My invention itself, however, both as to its organization and method of operation together with further objects and advantages thereof, may best be understood by reference to the following description taken in connection with the accompanying drawings, in which Fig. 1 illustrates the chassis of a radio receiver ywhich includes the tuning unit of my invention; Figs. 2 and 3 lare, respectively,

side elevational and perspective views, partly in section, of a portion of the chassis of Fig. 1 illustrating the constructional details of my improved tuning unit; and Fig. 4 is a view of a portionof an inductance tuner employed in the tuning unit of Figs. 2 and 3.

Referring to Fig. 1 of the drawings, I have illustrated therein at I a chassis in the form of the usual metallic box having supported on the upper surface thereof a plurality of electron discharge devices or radio tubes 2, a plurality of impedance elements 3 such as reactors, capacitors and intermediate frequency transformers, etc., yand a shield or container l which encloses the tuning Yunit of my invention. A panel 5 is atattached to the front of the chassis and arranged to support a, pointer assembly 6. Projecting from the front of the chassis are a plurality of shafts for controlling the operation of the receiver circuits, such as a volume control shaft 1, a tone control shaft 8, a band switch shaft 9, a line switch shaft I0, and a tuning shaft Il.

Referring now to Figs. 2 and 3 jointly, I Ihave there illustrated my tuning unit which comprises -a metallic supporting base I2 which is adapted to be supported from the upper surface of the chassis by means of a plurality of cushion mounts I3 and which supports on its upper surface three low frequency tuning coils Il, I5, I 6 and three high frequency vane tuners I1, I 8, I9. The coils III-I6 each comprises a winding which is supported on a tubular ldielectric form 20, in turn supported vertically by means of an insulating bushing 2| secured to the base I2. The resonance frequency of each of the coils I4-I9 is adapted to be varied over a wide range by means of ferromagnetic cores 22 formed, for examplafrom powdered iron and which are supported by means of thin rods orswires 23 from a horizontal platform 24 formed of a suitable insulating material. The rods 23 are attached to the platform 24 by passing through the apertures in threaded tubular sleeves 25 which screw into threads pro vided in the platform 24. After the cores 22 are adjusted with respect to windings I4-I9 to a desired position, the rods 23 may be soldered to the sleeves 25.4 y

The vane tuners I1-I9 each comprises a pair of parallel vertical supports 29, 21 each having on its inner surface a slot or guide 23 adapted slidably to receive a metallic vane 29. Attached to the supports 25, 21 are a pair of juxtaposed inductors 30, 3l, as may be best seen in Fig. 4. Each of the inductors comprises a peripherally incomplete metallic loop having a plurality of coplanar legs, each of which has a width much greater than its thickness. Moreover the loops or inductors 30, 3| have a plurality of outwardly extending taps 32 by means of which they may be riveted to the supports 23, 21. The inductors 30, 3i may be formed by punching out a fiat piece of metal to form a rectangle having an incomplete leg 33. Preferably inductors 30, 3i are of identical construction and in assembly one is oriented through 180 with respect to the other. As a result, the inductors 3II. 3l are so arranged with respect to the supports 23, 21 that the free ends of the legs 33 overlap and are secured together by means of a rivet 34. The other free end 35 of each of the inductors 30, 3i extends below the base I2 through apertures therein and provides means for connecting the inductors to the remaining elements of the receiver circuit. l

In accordance with my invention, the inductance of the coils I4I3 and the inductors Il-Ilmay be varied over a wide range simply by a1- lowing cores 22 and vanes 29 to descend respectively substantially freely in forms 20 and between theinductors 30. 3|. To effect such a tuning action, cores 22 are suspended as previously described and each of the vanes 29 is freely suspended from the platform 24 by means of a thin rod or wire 36 which extends through a tubular sleeve 31 screwed into threaded apertures provided in the platform 24. The lower ends of the wires 35 are soldered to the vanes 29 and the upper ends may be bent over through the aperture in the sleeve 31 until, by adjustment of the tube 31, the vanes 29 are so aligned with respect to the sets of inductors 30, 9| that desired inductance of each of the inductors I1-i9 is obtained. Thereafter, the upper ends of wires 33 may be soldered to the sleeves 31. Preferably wires 36 are sufficiently rigid that the vanes 29 move smoothly along guide 23. On the other hand wires 36 are sufficiently flexible that extreme accuracy in aligning the components of the vane tuners is not required.

Means are provided for supporting the ferromagnetic cores 22 relative to the coils I4-I9 and the tuning vanes 29 relative to the inductors i1-I9 and for simultaneously adjusting the positions of the tuning elements with respect to the inductive elements to tune the receiver circuits over desired bands of frequency. This means comprises a supporting post 33 which is apertures in the base I2 and a bracket 4I attached to the base I2 by means of screws 42. The platform 24 is adapted to be raised and lowered by means of a windlass comprising a slotted hoist pulley 43 and a supporting cable or wire 44. The cable 44 is attached at its lower `end to an arm 45 secured to the lower end of the post 33 and at its upper end to a tension spring 45 attached to the platform 24. Intermediate its ends, the cable 44 passes through aligned apertures 41 in the bracket 4I and the base I2 and the slots in the pulley 43. Several turns of the cable 44 are likewise wound around the hoist pulley 43. The pulley 43 is supported at one end of a shaft 43 supported in suitable bearings provided in the supporting bracket 4I. A drive pulley 49 is secured to the opposite end of the shaft 48 by means of a set screw 50. I provide braking means for the windlass which comprise a steel spring 5I attached to the bracket 4I and adapted resiliently to engage the shaft 48. Other braking means for holding the platform 24 in an adjusted position and aligning the post 33 vertically are provided and comprise a roller 52 supported from the upper portion of the bracket 4I by means of a resilient arm 53 and adapted, through the action of the resilient member 53, to exert a transveres force on the post 38.

The drive pulley 49 is adapted to be rotated by means of a driving cord or wire 54. one end of which is looped over the set screw 50 and the other end of which is attached to a tension spring provided within the drive pulley 49. Intermediate its ends, the cord 54 passes around a drive pulley 59 provided on the tuning shaft II and a plurality of idler pulleys 51 located at the four corners of the panel 5. The cord 54 is broken at its center and attached to the two ends of a connecting wire 59. The connecting wire 58 passes through slots provided in a spring member 59 attached to the pointer assembly 6 and adapted to engage firmly the wire 58 so that the pointer assembly moves with cord 54. A pointer 50 is likewise attached to the pointer assembly 5 and is adapted to cooperate with suitable tuning indicia or scales 6I engraved or etched upon a translucent panel 92 positioned in front of the panel 5. I provide means for facilitating the tuning of the receiver circuits and quick and easy traversing of scales 5I by means of the pointer 50 which comprises a flywheel 63 which is supported on the inner end of the tuning shaft Il. The flywheel preferably is formed by die casting a heavy metal, such as lead or zinc and has sufficient mass that the inertia thereof facilitates the tuning operations.

In embodying my invention in a radio receiver adapted to receive both standard broadcast signals and frequency modulated carrier waves varying over a high frequency band, the variable inductances I 4-Il may be connected, respectively, in the oscillator circuit, the radio frequency circuit, and in the antenna circuit of the receiver which circuits are used during reception of standard broadcast signals, i. e. frequencies between 550 and 1600 kilocycles. The inductors AI1--I9 may be connected, respectively, in the oscillator circuit, the radio frequency circuit, and the antenna circuit ofy the frequency modulation portion of the receiver circuits. In order to provide improved shielding of the circuits at the high frequencies employed for the frequency modulated signals and to reduce the coupling between the antenna circuit and the radio frequency circuit, the lnductor |9 is oriented in a plane transverse to that of the inductor I8. Furthermore, the bracket 4| is so constructed that it includes a portion 64 which is interposed between the inductors I8, |9. Tuning of both the broadcast and frequency modulation circuits is effected by a translating or linear motion of the ferromagnetic cores 22 and the metallic vanes 29. The inductance of the coils |4|6 is highest when the cores 22 are completely contained within the coils, while the inductance of the inductors |`l-|9 is greatest when the vanes are completely removed from a yposition between the turns 30, 3|. Accordingly, sufficient clearance must be provided below the coils |4|6 that the ferromagnetic cores 22 may project below the lower end of these coils for turning at one end of the broadcast frequency range. Similarly, sufficient clearance must be p rovided above the inductors |'|-|9 that the vanes 29 may project above the turns 30, 3| for tuning at the opposite end of the frequency modulation band. In this manner, the scales 6| all read in the same direction, that..l is, the pointer 60 moves across the scales in the same direction when the receiver circuits are tuned over the respective bands.

An important advantage of my invention is that it provides a tuner which may be constructed as a unit and included in a radio receiver with substantially no adjustment. The adjustment of the resonance frequencies of the individual coils is easily effected by adjustment of the position of the sleeves 25, 31 prior to the soldering of the Wires 23, 26 thereto. The vane tuners may be easily produced by stamping flat sheets of metal to provide both the inductors 30, 3| and the "vanes 29. Furthermore, the vanes and inductors may be so constructed that tracking of the antenna, radio frequency, and oscillator circuits is easily effected. Tuning is effected by rotating the drive pulley 49 by means of the tuning shaft and the cord 54 to cause the hoist pulley 43 to raise or lower the platform 24. Thus, the portions of the cable 44 adjacent the slots in the pulley 43 wind or unwind on the pulley to raise or lower the platform 24 and all of the tuning elements 22, 29. In raising the elements, they are pulled upwardly by attachment to the platform 24. In lowering them, the supporting post is allowed sufficient lateral movement and wires 23, 36 are sufficiently flexible that they jointly permit the cores 22 and the vanes 29 to descend freely within the dielectric tubes 20 and the slots 28. In this fashion tubes 20 act as guides for cores 22 and no accurate alignment is required. Furthermore, since the post 38 is rotatably supported by means of the bearings 40, 40' so that the platform 24 is free to rotate in a horizontal plane, unimpaired vertical movement of the cores 22 and vanes 29 is enhanced. Thus, the platform 24 rotates freely so that the problem of aligning the tuning cores and vanes with their respective windings and inductors is minimized. Thus, for example, if a coil form becomes displaced for any reason, as during shipment, the platform 24, under influence of the flexible supporting wires 23 and 36, adjusts itself in horizontal position to accommodate the new position of the displaced coil form and to a position where vertical movement of the different tuning elements takes place with a minimum of friction or impedance. y

Another important advantage of my improved high frequency tuner is that extremely short leads are required to connect the inductors 30, 3| to the remaining portions of the receiver circuit. The connections are easily made and the construction ofthe tuning elements is such that they are substantially unaffected by vibration or rough handling.

While my invention has been described by reference to a particular embodiment thereof, it will be understood that numerous modifications may be made by those skilled in the art without departing from the invention. I therefore aim in the appended claims to cover all such equivalent variations as come within the true s pirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. The combination, in an inductance device. oi' a horizontal frame having an aperture therein, a pair of vertically arranged tubular insulating members, coils wound respectively on said members, supporting means disposed above said members, bearing meansdisposed between said frame and said supporting means, a vertical shaft rigidly connected to said supporting means, said shaft being journalled in said bearing means and passing through said aperture, means for raising and lowering said supporting means, and a pair of ferromagnetic cores hung freely from said supporting means and arranged to ascend and descend in respective of said members as said supporting means is raised and lowered.

2. The combination. in an inductance device, of a horizontal frame having an aperture therein, a pair of vertically arranged tubular insulating members, coils wound respectively on said members, supporting means disposed above said members, bearing means disposed between said frame and said supporting means, a vertical shaft rigidly connected to said supporting means, said shaft being journalled in said bearing means and passing through said aperture, means for raising and lowering said supporting means, and a pair of ferromagnetic cores supported from said supporting means and arranged to ascend and descend in respective of said members as said supporting means is raised and lowered, the mechanical connection of said cores with said supporting means being sufficiently flexible and the diameter of said shaft being sufficiently small relative to the bore of said aperture that said cores move freely in said members despite misalignment thereof.

3. The combination, in a radio frequency tuning device, of a horizontal frame, a plurality of pairs of juxtaposed vertically mounted metallic loops supported on said frame, said pairs of loops being arranged for connection in different high frequency circuits, supporting means disposed above said loops, a plurality of metallic vanes supported from said supporting means, means for raising and lowering said supporting means with respect to said frame to move said vanes to positions interleaving said loops to vary the inductance thereof, one of said pairs being angularly disposed Wth respect to the other to reduce cou pling therebetween, and shielding means positioned between said pairs of loops.

4'. The combination, in an inductance device,

7 of a horizontal frame having an aperture therein, a pair of vertically arranged tubular insulat ing members, coils wound respectively on said members, supporting means disposed above said members, bearing means disposed between said frame and said supporting means, a vertical shaft rigidly connected to said supporting means, said shaft being journalled in said bearing meansand passing through said aperture, means for raising and lowering said supporting means, a pair of ferromagnetic cores hung freely from said supporting means and arranged to ascend and descend in respective of said members as said supporting means is raised and lowered, and means said shaft in an adjusted position.

5. The combination, in a radio frequency tuning device, of a frame member, a plurality of inductances supported vertically on said member, a platform disposed above said inductances, a plurality of tuningtelements for said inductances, and means for raising and lowering said platform relative to said member, said elements being supported from said platform and arranged to move relative to said inductances to vary the magnitude of said inductances as the position of said platform is varied vertically, said platform being supported for substantially free rotation in a L horizontal plane whereby as thel vertical position of said platform is varied said elements move freely with respect to said inductances.

6. vThe combination, in an inductance device,

of a horizontal frame member, a plurality of coil forms supported vertically on said member, each of said forms having an inductance wound thereon,` supporting means disposed above said forms, bearing means disposed between said frame and said supporting means, a vertical shaft rigidly connected to said supporting means, said shaft being supported in said bearing means for rotation and for movement in a direction normal to said frame, means for raising and lowering said supporting means, and a plurality of ferromagnetic cores supported from said supporting means and arranged for vertical movement in respective of said forms as said supporting means is raised and lowered. said supporting means being free to rotate in a horizontal plane whereby vertical movement of said cores in said forms is facilitated.

LEWIS H. VAN BILIIARD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED s'rs'rns PATENTS 

